A Non-Lipolysis Nanoemulsion Improved Oral Bioavailability by Reducing the First-Pass Metabolism of Raloxifene, and Related Absorption Mechanisms Being Studied

Figures & data

Figure 1 Excipient screening for NNEs. Consumption of NaOH by (A) oils, (B) surfactants, and (C) co-surfactants during the lipolysis; (D) Solubility of RAL in the excipients; (E) Emulsification efficiencies of surfactants; (F) Emulsification efficiencies of RH40 with different ratios of LA and IP.

Notes: Vs other oils, ^ap < 0.05, ^aap < 0.01; vs other surfactants, ^bp < 0.05, ^bbp < 0.01; vs other co-surfactants, ^cp < 0.05, ^ccp < 0.01.

Table 1 Emulsification Efficiency of the Co-Surfactants (n = 3)

Pre-NE ratio (LA:IP=1:2, w/w)	Assessment Indexes	Transcutol HP	Ethanol	1,2-Propanediol
3:5:2	Globule size (nm)	31.7 ± 0.5	22.4 ± 0.6	19.8 ± 0.8
	PDI	0.14 ± 0.01	0.25 ± 0.03	0.18 ± 0.02
	Phase separation	-	-	-
5:3:2	Globule size (nm)	95.7 ± 5.5	63.8 ± 4.6	109.9 ± 3.4
	PDI	0.30 ± 0.04	0.36 ± 0.02	0.34 ± 0.03
	Phase separation	Yes	No	Yes

Abbreviations: NE, nanoemulsion; PDI, polydispersity index.

Table 2 Composition and Characteristics of NEs in the Different Formulations

Pre-NE (1 g, w/w)	NNE1	NNE2	NNE3 *	LNE *
Mixed oil	LA:IP (1:2)	LA:IP (2:1)	LA:IP (2:1)	LA:SO (2:1)
Oils:RH40:Ethanol	3:5:2	3:5:2	5:3:2	5:3:2
RAL/pre-NEs (mg/g)	23.50 ± 1.76	27.75 ± 1.19	33.75 ± 1.05	35.50 ± 2.10
Globule size (nm)	63.8 ± 4.6	72.7 ± 1.3	53.5 ± 0.7	44.6 ± 0.4
PDI	1.40 ± 0.02	0.23 ± 0.01	0.15 ± 0.04	0.23 ± 0.09
Zeta potential (mV)	−1.75 ± 0.98	−1.74 ± 0.22	−0.95 ± 0.23	−1.97±0.42
Precipitation at 24 h	Yes	No	No	No

Note: *Optimal formulations of RAL-NNE and RAL-LNE.

Abbreviations: NNE, non-lipolysis nanoemulsion; pre-NE, pre-nanoemulsion; RAL, raloxifene; IP, isopropyl palmitate; LA, linoleic acid; SO, soybean oil; PDI, polydispersity index.

Figure 2 Characterizations of RAL-NNE and RAL-LNE. Globule sizes (A), morphology (B) of RAL-NNE and RAL-LNE (× 15,000).

Figure 3 Stability of RAL-NNE in gastrointestinal situation. (A) Stability in different media after dilution; (B) Lipolysis curves of RAL-NNE and RAL-LNE; (C) Content change of RAL in the NNE and LNE during and after the lipolysis; (D) UGT-mediated metabolism rates of RAL solution, RAL-NNE, and RAL-LNE.

Notes: *p < 0.05, **p < 0.01 ***p < 0.001.

Table 3 Bioavailability Parameters and Lymphatic Transport of RAL in Rats (n = 5)

		RAL (i.v.)	RAL-Control (i.g.)	RAL-LNE (i.g.)	RAL-NNE (i.g.)	RAL-LNE+CHX (i.g.)	RAL-NNE+CHX (i.g.)
Rat	Cmax (μg/mL)	1.89 ± 0.18	0.24 ± 0.12	0.72 ± 0.26 *	0.57 ± 0.08 *	0.15 ± 0.10 †	0.07 ± 0.02 †
	Tmax (h)	―	3.83 ± 1.47	2.67 ± 0.58	2.67 ± 0.58	3.00 ± 1.73	1.20 ± 0.45
	AUC0-24 h (h·μg/mL)	6.72 ± 0.20	2.12 ± 0.45	4.31 ± 0.57 **	4.36 ± 0.93 **	2.77 ± 0.82 ††	1.69 ± 0.66 ††
	AUC0-24 h- AUC0-24 hCHX (h·μg/mL)	―	―	―	―	1.54 ± 0.35	2.67 ± 0.33 #
	Fr (%)	―	―	203.30	205.89	―	―
	Fa (%)	―	7.01	14.25	14.43	―	―

Notes: *p < 0.05, **p < 0.01 vs RAL-control; ^†p < 0.05, ^††p < 0.01 vs CHX group; ^#p < 0.05, ^##p < 0.01 vs RAL-LNE+CHX.

Abbreviations: NNE, non-lipolysis nanoemulsion; LNE, lipolysis nanoemulsion; RAL, raloxifene; C_max, peak concentration; T_max, time to C_max; AUC, area under the curve; F_r, relative bioavailability; F_a, absolute bioavailability.

Figure 4 Plasma concentration-time profiles of RAL-LNE and RAL-NNE in rats (A) and pigs (B) after oral administration. Plasma concentration-time profiles of RAL-LNE (C) and RAL-NNE (D) in pigs.

Table 4 Bioavailability Parameters of RAL in Pigs (n = 3)

		RAL (i.v.)	RAL-Control (i.g.)	RAL-LNE (i.g.)	RAL-NNE (i.g.)
Pig	C^1max (μg/mL)	2.52 ± 0.11	0.42 ± 0.04	0.54 ± 0.05	0.42 ± 0.04
	C^2max (μg/mL)	―	―	0.46 ± 0.10	1.04 ± 0.11 *†##
	T^1max (h)	―	1.33 ± 0.45	1.58 ±0.72	1.33 ± 0.58
	T^2max (h)	―	―	15.33 ± 7.57 **	24.00 ± 0.01 **
	AUC0-24 h (h·μg/mL)	13.56 ± 3.08	3.44 ± 0.72	7.92 ± 0.36 **	18.62 ± 1.21 **††
	Fr (%)	―	―	230.23	541.28
	Fa (%)	―	4.31	9.93	23.34

Notes: *p < 0.05, **p < 0.01 vs RAL-control; ^†p < 0.05, ^††p < 0.01 vs RAL-LNE; ^##p < 0.01 vs C¹_max of RAL-NNE.

Table 5 Intestinal Absorption Parameters (K_a and P_eff) of the RAL-Loaded NNE Administered to Rats (n = 3)

	Segments	Ka ×10^−2/min^−1	Peff ×10^−3/cm·min^−1
RAL-NNE	Duodenum	10.01 ± 5.13	15.20 ± 8.40
RAL-NNE	Jejunum	21.39 ± 1.33	36.90 ± 6.83
RAL-NNE	Ileum	9.85 ± 2.32	17.75 ± 5.10
RAL-NNE	Colon	2.84 ± 1.39	4.05 ± 2.05
+ Amiloride	Jejunum	10.45 ± 1.36 **	11.07 ± 1.31 **
+ Chlorpromazine	Jejunum	3.30 ± 0.25 **††	3.14 ± 0.71 **††
+ Nystatin	Jejunum	3.28 ± 0.63 **††	2.83 ± 0.57 **††

Notes: *p < 0.05, **p < 0.01 vs RAL-NNE in the jejunum; ^†p < 0.05, ^††p < 0.01 vs + amiloride in the jejunum.

Abbreviations: NNE, non-lipolysis nanoemulsion; LNE, lipolysis nanoemulsion; RAL, raloxifene; P_eff, effective permeability; K_a, absorption rate.